Integrated circuits are formed through a process known as semiconductor device fabrication. The semiconductor device may be formed on a thin slice, or wafer, of semiconductor material, such as silicon crystal. The wafer serves as a substrate for microelectronic devices built on the wafer. During fabrication of these integrated circuits, the silicon wafer is put through a sequence of wet chemical processing steps. One wet chemical processing step in the sequence is electrochemical deposition, commonly known as electroplating.
In the electroplating process, electrical current is used to deposit metal ions from a solution onto a wafer, forming a film or patterned structure of metal on the wafer. Certain semiconductor packaging technologies, such as Wafer Level Chip Scale Packaging and Flip Chip, involve multiple electroplating steps. A proper size of a shield on the wafer holder is critical to achieve plating uniformity across the wafer surface during the electroplating process.
Currently, a wafer carrier 100 used for wafer plating is illustrated in FIG. 1. The wafer carrier 100 includes a wafer holder 110 and fixed size shield 112 mounted onto the wafer holder 110. The current method of shielding utilizes multiple fixed-size shields 112. Each of the fixed size shields 112 vary in size and dictate a fixed expose area for placement of a wafer 114. Since different sizes of the exposed area affect the plating uniformity, the fixed-size shields 112 have to be swapped during electroplating depending on the plating parameters. Swapping of the multiple fixed-size shields is commonly a manual operation which is tedious and lengthy. Also, the cost of creating such fixed-sized shields is very expensive. Further, locating the right fixed-size shield that matches the plating parameters is prone to error in wafer plating process.